1. Field of the Invention
The present invention relates to a semiconductor with protective elements, more particularly, to a bipolar-type semiconductor device, such as an emitter-coupled-logic (ECL) circuit device, having elements protecting against static electricity, the protective elements being compactly incorporated within the semiconductor device.
2. Description of the Prior Art
Generally, although bipolar-type semiconductor devices are more resistant to electrostatic destruction than metal-oxide semiconductor (MOS) devices, their tolerance voltage to electrostatic destruction has become lower along with the use of shallower junctions in the bipolar transistors and finer circuit patterns. This is especially true of ECL circuit devices. Therefore, in conventional bipolar-type semiconductor devices such as ECL circuit devices, elements has been incorporated into the semiconductor devices to protect against electrostatic breakdown destruction.
In conventional devices such as ECL circuit devices, however, each protective element is connected between an input terminal or an output terminal and a negative voltage-power supply lines. Since the negative-voltage power supply line is provided considerably apart from the input terminal or the output terminal, a wiring pattern for connecting each protective element and the negative-voltage power supply line is necessary. It is difficult to compactly incorporate the protective elements into the semiconductor device due to the wiring pattern.
In addition, conventional protective elements do not operate as transistors but only as a diode or diodes. Diodes conduct smaller current than transistors. Therefore, the capability of drawing abnormal charges is considerably low. Therefore, conventional semiconductor devices have considerably low tolerance voltage against electrostatic destruction.